Btukfyl

It is the horrifying scene from A Clockwork Orange, where they start Ludovico technique scene on Alex, forcefully clamping his eyes.

How did they shoot that scene? Did they really make Malcolm McDowell sit like that, because it seems painful. Also, it seems, you would have the urge to close eyes for that long time even if it is clamped whereas Malcolm McDowell did not act like wanting to close his eyes.

So, did they really shoot like that or was it some kind of video editing job. The scene feels like very much real though.

His eyes were clamped for real.

https://news.abs-cbn.com/image/entertainment/05/05/16/look-10-movies-that-nearly-or-actually-killed-their-stars-9

Though McDowell’s eyes were anesthetized during shooting, the clamps were actually attached to his eyelids. They were also being used incorrectly, with McDowell sitting upright rather than lying down. McDowell later said he was in excruciating pain during the entire shoot, suffered temporary blindness as a result of his eyes being forced open for so long, and ended up with a sliced cornea. Turns out those screams weren’t a result of great acting but rather just genuine torture.

As for:

Also, it seems, you would have the urge to close eyes for that long time even if it is clamped whereas Malcolm McDowell did not act like wanting to close his eyes.

It's not that he didn't blink. He really couldn't while the clamps were set.